The present invention relates to methods and apparatus for controlling operating parameters of a surface treating apparatus and specifically providing accurate adjustment of flow rates, chemical dilution ratios and/or scrubbing pressure.
Surface cleaning or treating apparatuses have been widely used and generally include a solution tank for storing and dispensing a cleaning solution, a scrub deck having one or more agitating elements such as in the form of brushes or pads for scrubbing a surface such as a floor with the cleaning solution, a tool such as a squeegee for collecting dirty solution, and a recovery tank for recovering the dirty solution from the floor through a hose. Most often, the cleaning solution is a mixture of a cleaning chemical and clean tap water. Traditionally, the chemical was simply added into the solution tank, and the entire tank became a mixture of clean water and chemical. The dilution ratio of the water/chemical mixture could not be exactly controlled, for it depended on the person pouring the chemical into the solution tank.
In recent years, chemical injection has become a common feature for surface treating apparatuses. Typical chemical injection systems include a separate cleaning chemical storage container mounted on the surface treating apparatus. A mechanism is utilized to dispense a controlled amount of chemical into the clean water, at or near the point of use. These chemical injection systems are more accurate in chemical metering. In order to be able to control the chemical dilution ratio, both the clean water and chemical flow rates must be controllable. The flow rate of the cleaning solution can be controlled by different ways including: gravity feed without adjustment, which is least accurate; gravity feed with a manually adjusted ball valve; gravity feed in conjunction with an electronically pulsed solenoid valve; and feed with a pump.
U.S. Pat. Nos. 6,105,192 and 6,301,738 disclose a solenoid valve and timing module kit for use with a floor treating apparatus using gravity feed in conjunction with the solenoid valve pulsed electronically. The timing module continuously opens and closes the solenoid valve in response to operator control. The introduction of surface treating apparatuses represented by U.S. Pat. Nos. 6,105,192 and 6,301,738 obtained significant advantages in the marketplace in eliminating conventional ball or needle valves that are always open when the cleaning solution is supplied, in creating anything from a trickle to a full flow of the cleaning solution, in allowing an operator to generally maintain flow of the cleaning solution, and in minimizing any lag time in starting or stopping the supply of the cleaning solution to a floor treating device by locating the solenoid valve immediately above the supply points. However, even such an innovative and commercially successful apparatus has need for further improvement. In particular, in gravity feed systems including the type represented by U.S. Pat. Nos. 6,105,192 and 6,301,738 as well as other types, the level of the cleaning solution or water in the solution tank drops due to dispensation of the cleaning solution or water and, thus, affects the maximum flow rate of the solenoid valve, leading to a decrease in the flow rate of the cleaning solution and to an increase in the chemical dilution ratio, both of which are undesired. The operator control for maintaining the constant flow of the cleaning solution is not always accurate. Furthermore, currently available surface treating apparatuses do not allow accurate adjustment of the scrubbing pressure during operation.
Thus, a need exists for methods and apparatus providing accurate adjustment of a flow rate of cleaning solution, a chemical dilution ratio and/or scrubbing pressure in surface treating apparatuses.